This door is part of an old water powered woolen mill in Pennsylvania that dates to 1830. It is so old they made blankets for the Union Army here during the Civil War, and the machinery is still inside in working condition! The looms running on leather belts make the patterns from cards with punched holes, much like an early computer. They still make blankets for Civil War reenactors to this day with US Army woven into them, although it is done with electric motors nowadays because the waterwheel is inoperative yet the pond and dam are still there.
Back in the day, there were many shepherds with flocks of sheep in the area who would bring clipped wool here for spinning and manufacture, but today spun wool is brought in from elsewhere. To see the type of heavy and coarse wool blankets made here, see image #14029 that also shows some of the original wooden bobbins that were used here.
The building itself is built on a solid foundation of local limestone that still stands square with two more wooden stories above, with most of the machinery on the second floor. This main door and lockset that uses a skeleton key may very well be original, and the title of Lucky Welcome is from the lucky horseshoe above the door. Look up Waterside Woolen Mill in Woodbury PA on Facebook for more information.